PVC Pipe Pressure Rating Chart — Schedule 40 & 80 per ASTM D1785
PVC 1120 water pressure ratings at 73 °F for Schedule 40 and 80 pipe per ASTM D1785, with the standard temperature derating factors.
Updated August 20, 2026
A PVC pressure rating is pure hoop-stress arithmetic: ASTM D1785 rates each pipe at P = 2·S·t/(D − t), where S is the 2,000 psi hydrostatic design stress of PVC 1120 compound for water at 73 °F, t is the minimum wall, and D is the outside diameter. That is why small pipe carries startlingly high ratings (thick wall relative to diameter) and why Schedule 80, with its heavier wall, always outrates Schedule 40 in the same size. The ratings below are the published D1785 Appendix X1 values for unthreaded pipe; the walls and ODs behind them are tabulated in the pipe schedule chart, and a test recomputes every rating from those dimensions.
Two derates matter in practice. Temperature: the 73 °F rating falls fast as the fluid warms — at 100 °F the pipe keeps only 62% of its rating, at 140 °F (the maximum service temperature for PVC) just 22%. Threading: cut threads halve the wall at the root, so threaded Schedule 80 pipe is rated at 50% of the plain-end values below, threading Schedule 40 is not an accepted practice at all, and manufacturers advise against threaded PVC joints above 110 °F. Ratings are for water without surge; pressure spikes from valve slam ride on top of the working pressure and must be added before comparing against the rating.
PVC 1120 Water Pressure Ratings at 73 °F — ASTM D1785 (Unthreaded)
| Nominal size | Schedule 40 (psi) | Schedule 80 (psi) |
|---|---|---|
| 1/2" | 600 | 850 |
| 3/4" | 480 | 690 |
| 1" | 450 | 630 |
| 1-1/4" | 370 | 520 |
| 1-1/2" | 330 | 470 |
| 2" | 280 | 400 |
| 2-1/2" | 300 | 420 |
| 3" | 260 | 370 |
| 4" | 220 | 320 |
| 6" | 180 | 280 |
Published D1785 Appendix X1 ratings for PVC 1120 (cell class 12454), water, non-shock, plain-end pipe. Ratings follow P = 2·S·t/(D − t) with S = 2,000 psi, rounded to the nearest 10 psi. Threaded Sch 80 pipe is rated at 50% of these values. Dimensions behind each rating are in the pipe schedule chart.
Temperature Derating Factors — Multiply the 73 °F Rating
| Operating temperature | Derating factor |
|---|---|
| 73 °F | 1.00 |
| 80 °F | 0.88 |
| 90 °F | 0.75 |
| 100 °F | 0.62 |
| 110 °F | 0.51 |
| 120 °F | 0.40 |
| 130 °F | 0.31 |
| 140 °F | 0.22 |
Manufacturer engineering data (Harvel / U.S. Plastic), applied industry-wide: maximum working pressure = 73 °F rating × factor. 140 °F is the maximum service temperature for PVC. Use solvent-cemented joints near the limit; threaded connections are not recommended above 110 °F.
Sources & Further Reading
- ASTM D1785-12 — PVC Plastic Pipe, Schedules 40, 80, and 120: Appendix X1 hydrostatic design stresses (PVC 1120 = 2,000 psi for water at 73 °F) and Tables X1.1/X1.2 pressure ratings (read directly from the standard)
- Harvel Plastics PVC Industrial Pipe Schedule 80 product specification — working pressures and temperature derating factors (digit-identical to the D1785 X1.2 unthreaded column; 50% threading derate)
- Westlake Pipe & Fittings PL-PS-001 (ASTM D1785 Sch 40/80 submittal) — independent digit verification of every Sch 40 and Sch 80 rating; U.S. Plastic Corp. knowledgebase — independent verification of all eight derating factors
Frequently Asked Questions
Why does 2-1/2 in pipe have a higher rating than 2 in pipe?
Because the rating tracks the wall-to-diameter ratio, not the size. The 2-1/2 in size jumps to a proportionally thicker wall (0.203 in Sch 40 versus 0.154 in for 2 in), so its hoop-stress rating rises to 300 psi against 280 psi — one of several places where the schedule system's wall steps outpace the diameter growth. The same wobble appears in steel schedule tables, which use the same walls.
What pressure can Schedule 40 PVC handle at 100 °F?
Take the 73 °F rating and multiply by the 100 °F factor of 0.62. For 1 in Sch 40: 450 × 0.62 = 279 psi. For 4 in: 220 × 0.62 = 136 psi. The factors fall steeply because PVC softens with heat — by the 140 °F service limit only 22% of the rating remains, and above that the pipe itself distorts.
Can I thread PVC pipe?
Only Schedule 80 or heavier, and at half the rating: cutting threads removes roughly half the wall at the thread root, so a 1 in Sch 80 pipe drops from 630 psi plain-end to about 320 psi threaded. Schedule 40 wall is too thin to thread at all — use solvent-weld socket fittings. Manufacturers also advise no threaded PVC connections above 110 °F; use flanges or unions where disassembly is needed hot.
Do these ratings cover water hammer?
No — they are for steady, non-shock water pressure. Surge from fast-closing valves adds a spike on top of the line pressure (roughly 25 psi per ft/s of arrested velocity in PVC), and the working pressure plus surge must stay within the rating. Keeping design velocity near 5 ft/s is the usual manufacturer guidance for pressure PVC systems.
Try the Calculators
PVC Pipe Pressure Rating Chart — Schedule 40 & 80 per ASTM D1785 — reuven.tools/reference/pvc-pressure-ratings — verified against: ASTM D1785-12 — PVC Plastic Pipe, Schedules 40, 80, and 120: Appendix X1 hydrostatic design stresses (PVC 1120 = 2,000 psi for water at 73 °F) and Tables X1.1/X1.2 pressure ratings (read directly from the standard); Harvel Plastics PVC Industrial Pipe Schedule 80 product specification — working pressures and temperature derating factors (digit-identical to the D1785 X1.2 unthreaded column; 50% threading derate); Westlake Pipe & Fittings PL-PS-001 (ASTM D1785 Sch 40/80 submittal) — independent digit verification of every Sch 40 and Sch 80 rating; U.S. Plastic Corp. knowledgebase — independent verification of all eight derating factors